Proteomics is the systemic evaluation of protein levels in the body and correlation with pathogenic and physiologic states. They can be analyzed individually or as a pattern, the latter being accomplished by algorithms run by computers. Proteomics can be used to identify biomarkers of early disease like in cancer as well as to identify drug targets, efficacy markers, and toxicity markers of drugs. Its advantage over genomics lies in the measurement of real-life changes in gene expression. Genomics and proteomics, when correlated together, help in understanding systems biology. While microarrays and immunoassays detect proteins based on antigenic property, mass spectrometry relies on charge and mass of proteins.